TORONTO — Faced with floundering interest in the BlackBerry as the business phone of choice, Research In Motion Ltd. took the final step Tuesday towards accepting a reduced role.

Waterloo, Ont.-based RIM rolled out the full version of its BlackBerry Mobile Fusion platform — which allows corporate BlackBerry networks to manage Apple Inc. devices such as the iPhone or iPad as well as Google Inc. Android-based devices — the same day the company was hit with yet another lawsuit and a report saying BlackBerry’s anemic share of the United States smartphone market is still bleeding out.

The bad news helped erase the gains the beleaguered stock made last week when new chief executive Thorsten Heins hinted at some willingness to consider a sale. By the close of markets on Tuesday RIM’s Toronto Stock Exchange shares had fallen $1.37 or 9.6% to $12.88, pennies above its 52-week low.

According to market research firm comScore Inc., just 13.4% of more than 104 million U.S. smartphone owners used a BlackBerry as of late February, said in its latest MobiLens report. That slice is a 3.2 points smaller than the 16.6% of pie RIM held last November.

As recently as February 2010 BlackBerrys represented more than 42% of the U.S. smartphone market, and the tailspin in which RIM’s share has remained trapped since then has contributed to a drop of more than 80% in the company’s share price.

Also depressing the share price was news that NXP Semiconductors NV, a Dutch tech firm, had filed a lawsuit against RIM on Monday alleging the Canadian company knowingly infringed on several of its patents related to device design and data transmission. RIM is frequently the target of intellectual property lawsuits and last summer paid US$770-million for patents originally filed by defunct telephony giant Nortel Networks Corp. to solidify its IP war chest.

After announcing last week RIM’s fifth straight quarter (his first as CEO) of failing to meet Wall Street’s expectations for quarterly earnings, Mr. Heins vowed to place more focus on rebuilding RIM’s waning dominance in the enterprise market. While the smartphone market is still nascent and some observers point to the possibility of the market simply expanding faster than the BlackBerry user base, chief financial officer Brian Bidulka cautioned analysts last week “we do not expect to grow our U.S. subscriber base as quickly as we did in 2012.”

One analyst on the call noted about two million new subscribers, bringing the total to 77 million worldwide, represented only half RIM’s usual user growth rate and asked for clarification. Management did not address the question directly.

Mr. Heins did acknowledge RIM’s “extremely challenging” position in North America on the call, which analysts considered a refreshing departure from the “stay tuned” mantra oft-repeated by former co-CEO Jim Balsillie, who along with company founder Mike Lazaridis stepped down in late January amid intensifying criticism. Mr. Heins said “BlackBerry cannot succeed if we try to be all things to all people.”

“Part of the reason for our market position right now is because we were so fragmented, but we are bringing it all together now” he said, also admitting “RIM was late to the bring-your-own-device movement and I am committed with my team to reclaiming lost market share in the space.”

By launching Mobile Fusion with many of the same features and pricing structure as the BlackBerry Enterprise Server, RIM is making good on a promise made last May to extend its famously secure business device management platform to non-BlackBerry devices, with the clear hope of relegating them to the minority. Yet Colin Gillis, senior technology analyst at BGC Partners in New York, remains unconvinced the move will herald a return to RIM’s glory days of dominance in the business world.

“This is a good step [and] at least they are showing more reality about the marketplace, but the days of having the enterprise [market segment] locked up 100% are over,” he said. “It is going to be a rough six months ahead at least for this company.”

Part of the reason for RIM’s fall from the peak of the mobile pyramid has to do with the comparatively limited ecosystem of software applications the company offers its users. Slightly more than 15,000 apps have been released for RIM’s seven-inch touchscreen PlayBook tablet, while several hundred thousand apps exist for the ecosystems controlled by Apple and Google.

RIM has been attempting to counteract that growing imbalance with incentives for developers to build BlackBerry apps and a growing focus on compatibility with platform-agnostic HTML5-based software. The company also plans to give away as many as 2,000 BlackBerry 10 devices to developers in May in hopes of having an ecosystem in place ahead of the new platform’s launch still set for this year.

“With BB10 we are getting ready for not just a software launch, we are getting ready for the mobile computing platform of the next decade,” Mr. Heins said last week, echoing the dramatic flair of his predecessors.